The aim of this proposal is to obtain funds to upgrade our flow cytometry facility. Presently, the University has a FACS III with a single laser capable of operating only in the visible light range. Due to increased demand for the use of broader range of machine capabilities, it is proposed to purchase a FACS 440 with a dual laser optical bench and both log and linear amplifiers. The present machine will be either traded back to Becton-Dickinson or sold to another research institution in the area, thus defraying the cost of the upgraded equipment. The current facility is used by a number of researchers both in the medical center and the main campus. However, there is an urgent need to meet the requirements of an even larger body of the scientific community. Projects that use this facility include basic research in immunology, cell and developmental biology, as well as a variety of clinical projects.